Irithyll is the next area after the Catacombs of Carthus. It's also the first area of the game that will make a proper effort to munch you, at least until you get past the first area, but once you find the bonfires you'll have more freedom to explore. This guide will give you the breakdown on how to find the bonfires, as well as the most useful shortcuts and key items to pick up, but without spoiling too many of the secrets or illusory walls you can find for yourself.
How to get into Irithyll of the Boreal Valley
To get to Irithyll proper you cross over a long stone bridge. After you get a quarter of the way across a guard dog will appear behind you, and 'dog' that should be read as 'huge wolf thing that does a lot of damage and has teeth on its belly ' (this latter point being to outfox the tactic of hiding under the tummy of giant monsters to avoid damage).
You have two options: run and hope that you make it over the bridge in time - which is possible, and if you do manage it the beast will disappear, but will turn up later when you run below the bridge - or turn to fight it. If you pick the latter you'll need to know that it can also shoot electricity from its mouth and you should dodge to the side rather than directly forwards because it can and will pick you up in its mouth.
In either case you won't actually be able to get over the bridge without having killed the Deacons of the Deep and collecting the Small Doll they drop. Without this you can't get through the invisible barrier on the other side of the bridge (which is inconvenient if you picked the run away option).
Irithyll of the Boreal Valley bonfire in Dark Souls 3
After you've defeated High Lord Wolnir in the Catacombs of Carthus, go up the stairs at the end of his boss area, you'll come out and look upon a beautiful city, dusted with snow and rising up against a backdrop of aurora burning in the sky.
This city will do its very best to destroy you.
Central Irithyll bonfire in Dark Souls 3
Once you've crossed over the bridge you'll be at the foot of the city, and the bonfire will be on your right. There are a few items scattered around this area, so sweep 'em up.
Church of Yorshka bonfire in Dark Souls 3
Getting up to the next bonfire can be a challenge, since the game now throws a bunch of enemies at you that aren't necessarily hard to take out, but can do a lot of damage and will be attacking you in groups. It may be easier to just run through rather than stopping to attack them all. So, from the Central Irithyll bonfire run up the stairs opposite, with three tall, thin enemies, and keep following the hill up as it curves around to the left. You'll come to a round courtyard with a fountain. Run left and avoid the procession of enemies, and keep heading up again, past two more of the thin enemies. As you near the top of the hill you'll be naturally drawn to a lit altar that you can see between an archway, but you need to run left again, up a curved flight of stairs, and into a dilapidated, falling down church. The bonfire is in the middle of it.
If you helped out Anri of Astoria in the Catacombs of Carthus then they'll now be chilling out in the church, and will give you a ring. One of the statues in the corner of the room is an assassin, and depending on which storyline you're following you can either kill them or leave them be.
Distant Manor bonfire in Dark Souls 3
From the Church of Yorshka bonfire head down the stairs and left, down another staircase which passes under a bridge. This curves around into a very dark cellar-like building where a torch is, if not totally necessary, then at least very advisable. Heading straight on as you exit those stairs will take you out of the cellar, but you can also go to the right and up a ladder, which takes you into the rafters where you can loot some useful items.
As you leave this area you'll find yourself overlooking a shallow lake, and the bridge you crossed to enter Irithyll is over your head. Enter the water and splash your way left, (as you pass under the bridge this is where the wolf creature will appear if you didn't kill it on the bridge earlier) and keep going, past a low arch entrance to a sewer on your left, towards a building with a doorway in front of you. Past this doorway is a new bonfire.
Pontiff Sulyvahn bonfire in Dark Souls 3
Appears after you defeat the boss Pontiff Sulyvahn.
Water Reserve bonfire in Dark Souls 3
Alright, this is an almost secret bonfire. After Pontiff Sulyvahn there's a good deal of Irithyll that you still have to get through to reach the next area. After you leave the boss area through the back of the church, head left and then right, either running through the sleeping giants (two of which will wake up) or crossing straight over the stairs into the covered area to the left of said giants, out of the door there, and up and over through the fireball throwing deacons. Either way, go through the doorway at the other end and then hit the wall on your left. This will vanish to reveal a ladder, leading down into what is basically a sewer, with two of the terrible giant wolf things lurking in it. If you manage to kill them you can light a bonfire here, as well as pick up the Aldrich Faithful Covenant.
Shortcuts at Irithyll of the Boreal Valley in Dark Souls 3
There are two main shortcuts that you want to worry about, really. The first will open up half the city so you don't have to keep going down to the lake and back up again. From the Distant Manor bonfire go back to the lake and into the sewer you ran past earlier, which will now be on your right. This area is full of disturbing eldritch insect-like creatures, but what else is new in Dark Souls? Roughly opposite the entrance to this area is a flight of stairs that leads up into what appears to be a normal kitchen.
Leave the kitchen and enter a large hall. There's a silver knight at the end furthest from you and two more up in the wings (this area has a lot of cool chests which aren't actually mimics, for once, so it's worth exploring). Go out of the house and up some shallow stairs - feat. many dogs - and pause when you come to a flat area with another flight on your right. On your left is a lift room. Take the lift up and open the gate at the top to open up a shortcut to the Church of Yorshka bonfire, by crossing the main plaza.
The second shortcut opens a gate between that allows you to run through from the Church of Yorksha bonfire and the boss fight area. Go to the bottom of the lift from the first shortcut and run up the stairs opposite, following them left and into a new room with another set of stairs. Run up these and out of the room, to yet more stairs. These lead to the courtyard before the main church, and you can see the fog door indicating the boss fight on your left. To open the shortcut you need to run straight past it and down the flight of stairs opposite those you just came up. You'll see some gates at the bottom of them which you can push open.
Key Items at Irithyll of the Boreal Valley in Dark Souls 3
Roster of Knights
From the Church of Yorshka bonfire go down the stairs that lead out of the side of the Church (if you fast travel to the bonfire you'll be facing the stairs when you appear). Turn immediately right at the bottom of them and go into a dead end with a corpse against the back wall. This guy has the Roster of Knights on him, which is a multiplayer item listing players who've joined the Darkmoon Knights, a covenant you can get in on a bit later in the game.
Undead Bone Shard
After going down the staircase described above, head out onto a cliffside. Swing right and head up the hill and around. You'll come to a large gravestone with a corvian enemy from the Road of Sacrifices in front of it. Behind the gravestone is the shard, which you can now throw on the bonfire at Firelink Shrine and increase the power of your estus flask.
Possibly the weirdest ashes you can give to the Firelink Shrine Handmaid that you have yet found. From the Distant Manor bonfire go back out onto the lake and into the sewer full of weird insect enemies. At the bottom of the stairs leading up into the kitchen area there's an alcove which has the ashes in.
Aldrich Faithful Covenant
In the room with the Water Reserve bonfire you'll find Archdeacon McDonnell lurking in a corner, who'll give you the covenant. This covenant is more of a nasty than a nice one (Aldrich himself not being the friendliest chap). If you can't kill the two giant wolf watchdog things in here then you can also grab the covenant by running in, speaking to McDonnell, and then running away again, but it's a very risky business.
From the Water Reserve bonfire (or, if you haven't opened that, after running past the giants and deacons after the Pontiff Sulyvahn bonfire) you'll head up some stairs and out onto some rooftops, similar to the ones you ran over at the Cathedral of the deep. Run up the thin roof walkway furthest on the right, then up again to a ledge where some silver knights have been determinedly firing arrows from, and head right, down and around a staircase to a flat paved area that is, if we're honest, a dead end. But a dead end with a corpse on it! Loot the body for your ashes, which you can give to the Shrine Handmaid.
Where to find Siegward of Catarina at Irithyll of the Boreal Valley in Dark Souls 3
If you've kept with Siegward so far, and gave him back his armour when he was trapped in the well at the Cathedral of the Deep, you can run into him again. Start at the Distant Mansion bonfire and run through the sewer full of insects and up into the kitchen area. Siegward is hanging out here, and has even made some Estus Soup. Good lad.
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